[22.07] Spectroscopy of the nova-like system UX UMa and two classical novae: V603 Aql and BT Mon

J. Arenas (Universidad de Concepcion)

This dissertation involves the study of three interacting
binary stars: V603 Aql (Nova Aquilae 1918), BT Mon (Nova
Monocerotis 1939) and UX UMa. UX UMa is the prototype-star
of a major sub-class of nova-like systems. Using
time-resolved spectroscopic data on V603 Aql, and
time-resolved spectrophotometric data on UX UMa and BT Mon,
I performed photometric and spectroscopic analyses, as well
as Doppler tomographic studies and Eclipse mapping of these
three CVs. In V603 Aql, I found evidence, for the first time
in spectroscopy, for negative and positive superhump periods
in the emission lines and the continuum. The superhump
periods found in the continuum and line variations in V603
Aql are consistent with other, photometric, observations.
The structure of the accretion disc in UX UMa, based on the
models used in this dissertation, is characterized by two
regions. An inner accretion disc which is characterized by a
blue continuum with absorption lines, which cross over to
emission with increasing disc radius. In the case of BT Mon,
in my data, the system shows evidence of an accretion disc
which is eclipsed by the secondary producing the broad
eclipses observed, but a large fraction of the luminosity
came from an accretion spot. This can explain the
single-peaked emission lines observed in the spectra. Some
authors have identified V603 Aql as permanent superhumper
(PSH) based on the fact that the photometric period
(Psh) is different from the spectroscopic period
(Porb), and it has been suggested that the PSHs may
represent a subgroup of CVs with mass ratios q<0.3 and
high mass transfer rates. My results confirm that V603 Aql
shows evidence of instabilities associated with the
accretion disc which are the cause of the variations
observed.